Table of Contents 1998

We produce about 600 to 800 cubic yards of ready-mixed concrete a day, but it seems like we never have enough trucks to take care of our customers' needs. Almost every day we have to deny some of them trucks. We don't want to buy more trucks because we're worried about being stuck with extra trucks...

We produce precast exposed-aggregate sandwich panels using concrete made with Type III cement, a 0.38 water-cementitious materials ratio and enough superplasticizer to achieve a 7- to 8-inch slump. The forming bed is made of wood. Using a bucket that passes down the center of the bed, we pour...

Our hauler delivered a load of concrete sand in a truck that had previously hauled urea. We batched the sand in several truckloads of concrete used in the walls for a residential basement. When finishers placed the basement floor, they complained about a strong ammonia smell, and that's when we...

I'm promoting the use of precast-concrete prison-cell modules in our state and need some backup information to help me do it. Are there any articles that can help me to explain the advantages and methods for this kind of construction?

We want to buy a jig to float out some of the opaline shale in our sand source. The shale is reactive and we need to reduce the expansion when the sand is tested by either ASTM C 1260, "Standard Test Method for Potential Alkali Reactivity of Aggregate," or C 1293, "Standard Test Method for Concrete...

We supplied concrete for a slab that now has a number of cracks in it. The owner thinks drying shrinkage caused the cracks and believes our concrete is at fault, but the concrete was placed on a hot, dry, windy day, so we think the cracks were caused by plastic shrinkage. Can visual examination...

I do a lot of troubleshooting on residential concrete flatwork -- mainly sidewalks or driveways. Is there a way to tell the difference between structural cracking caused by overload or soil movement, and nonstructural cracking caused by volume changes related to drying shrinkage or thermal...

What causes crazing on architectural precast products? Does it affect structural integrity, or is it just an aesthetic problem? How do you minimize it without sacrificing the 5000-psi compressive strength usually specified for architectural precast products?

We're supplying concrete for a tilt-up project that requires concrete with a 3500-psi (25 MPa) 28-day compressive strength. In addition to making standard test cylinders, the tilt-up contractor is also making beams that are stored in the field before they're tested. Because of nonstandard curing...

My belief is that increasing the cement content in mixes designed for placement in conditions below 32° F is counterproductive to initial strength gain due to the additional hydration required to generate heat. We use a Type III cement and generally deliver concrete at 60° F at time of placement...